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Active noise control using variable step-size adaptation

a technology of active noise and step-size adaptation, applied in the field of processing signals, can solve the problems of noise generation and noise being more destructiv

Active Publication Date: 2018-12-25
BLACKBERRY LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This approach ensures stable and effective noise cancellation across varying acoustic conditions, preventing system instability and noise introduction, while allowing for flexible adaptation rates to optimize noise reduction at different frequencies.

Problems solved by technology

However, when acoustics change or when a noise occurs unexpectedly, the system may quickly converge to an extreme operating state that pushes the system into instability and causes it to generate noise, rather than suppressing the undesired signals.
The noise may be more destructive than the undesired signals the system intends to cancel.

Method used

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  • Active noise control using variable step-size adaptation
  • Active noise control using variable step-size adaptation
  • Active noise control using variable step-size adaptation

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Embodiment Construction

[0010]An active noise control system and method (referred to as the system(s) or ANC system(s)) actively reduces undesired sound within a specific spatial region, called the primary noise field, by adapting one or more secondary signals rendered from one or more transducers or loudspeakers that destructively interfere with the primary noise field. The secondary noise field rendered by the loudspeakers has roughly the inverse sound pressure polarity of the undesired primary noise field, which effectively reduces or substantially eliminates the primary noise field. The system generates the secondary signals by filtering one or more reference signals through one or more control filters. The control filters are dynamically adapting based on signals from one or more error microphones that are placed within the spatial region. The control filter adaptation is also dependent upon secondary path filters that are estimated a priori through a calibration process. This allows compensation for ...

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Abstract

A system and method (referred to as the system) that actively reduces noise in a vehicle. The system generates one or more control output signals to drive multiple loudspeakers; and adapts multiple control coefficients of a control filter based on multiple secondary path transfer functions. The secondary path transfer functions model the acoustic paths between each loudspeaker and multiple microphones. The multiple control coefficients are time varying and frequency dependent and the rate the plurality control coefficients adapt is based on an adaptive step size based on one or more step size criteria.

Description

BACKGROUND OF THE DISCLOSURE1. Technical Field[0001]This disclosure relates to processing signals and in particular, to a system and method that maintains stability and reduces low-frequency noise through variable step-size adaptations.2. Related Art[0002]Active noise control analyzes input signals and generates output signals to cancel undesired signals in a spatial sound field. Through feedback that returns a portion of the system's output to the system's input, the system maintains accuracy and stability in ideal and theoretical conditions. However, when acoustics change or when a noise occurs unexpectedly, the system may quickly converge to an extreme operating state that pushes the system into instability and causes it to generate noise, rather than suppressing the undesired signals. The noise may be more destructive than the undesired signals the system intends to cancel.BRIEF DESCRIPTION OF THE DRAWINGS[0003]This disclosure refers to the following drawings and descriptions. T...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): G10K11/178
CPCG10K11/178G10K2210/1282G10K2210/12821G10K2210/3055G10K2210/3046G10K2210/3054G10K2210/3028G10K11/17823G10K11/17853G10K11/1785
Inventor EVERY, MARK ROBERT
Owner BLACKBERRY LTD